The present invention relates to product testing, and more specifically to testing a product for leaks.
Many products are produced in an air-tight manner for environmental, health, freshness, operational and/or other reasons. To meet the need for air-tight products, test equipment have been developed to test certain types of products for leaks. For example, U.S. Pat. No. 5,861,546 (""546 Patent) to Sagi et al., the disclosure of which is hereby incorporated by reference, discloses a leak detection apparatus that is suitable for detecting leaks in a product having an opening to which a leak sensor and a vacuum system may be coupled in order to form a closed test system.
All pressure values provided are absolute pressures (i.e. not gauge pressures) unless otherwise indicated. The present invention utilizes technology which the Applicant has named xe2x80x9cMass Extraction Technologyxe2x80x9d. A leak detection sensor that embodies Mass Extraction Technology generally measures the amount of total mass or mass flow of air or any other gas extracted from a product while the product is exposed to a constant vacuum. The mass extracted is related to a virtual defect size or virtual pin hole size of the product under test. Since at a given temperature and pressure, mass and volume of a gas are correlated, a leak detection sensor that embodies Mass Extraction Technology may alternatively measure the amount of total volume or volumetric flow of air or any other gas extracted from a product while the product is exposed to a vacuum. Leak detection sensors embodying the Mass Extraction Technology of the present invention can be manufactured to be extremely sensitive and measure levels as small as 1*10xe2x88x926 std. cc/sec. or 0.15 micrograms/min at 0.133 KPa. Due to this extreme sensitivity with any gas, leak detection sensors of the present invention can be used to perform tests with inexpensive gases such as air or nitrogen which previously required much more expensive techniques and gases such as Helium Mass Spectrometry.
Pursuant to an exemplary embodiment, there is provided a method of testing a product for leaks. One step of the method includes applying to the product a reference pressure that is less than 50.6 KPa. Another step of the method includes developing a gas flow through a leak detection sensor in response to applying the reference pressure to the product. The method also includes the step of determining, based upon the gas flow between the product and the pressure system, whether the product leaked an unacceptable amount during the test period.
Pursuant to another exemplary embodiment, there is provided a leak detection system for testing a product for leaks. The leak detection system includes a chamber dimensioned to receive the product, a pressure system that maintains a pressure of less than 50.6 KPa during a test period, and a leak sensor coupled to the chamber via a first conduit and the pressure system via a second conduit. The leak sensor is operable to receive the reference pressure via the second conduit and apply the reference pressure to the chamber via the first conduit. The leak sensor is also operable to develop a gas flow from the chamber through the leak sensor to the pressure system as a result of applying the reference pressure to the chamber. The leak sensor is further operable to determine, based upon the gas flow between the chamber and the pressure system, whether the product leaked an unacceptable amount during the test period.
Pursuant to yet another exemplary embodiment, there is provided a leak detection system for testing a product having an opening for leaks. The leak detection system includes a pressure system that maintains a pressure of less than 50.6 KPa during a test period, and a leak sensor coupled to the opening of the product via a first conduit and the pressure system via a second conduit. The leak sensor is operable to receive the reference pressure via the second conduit and apply the reference pressure to the product via the first conduit. The leak sensor is also operable to develop a gas flow from the product through the leak sensor to the pressure system as a result of applying the reference pressure to the product. The leak sensor is further operable to determine, based upon the gas flow between the product and the pressure system, whether the product leaked an unacceptable amount during the test period.